1. Field of the Invention
This invention relates in general to protective devices for use in active sports and work activities such as in-line skating, skateboarding, roller skating, tile-laying, gardening and the like. More particularly, the invention relates to protection of the limbs of people engaged in those activities.
2. Description of the Related Art
Protection devices such as knee and elbow pads are commonly used in sports such as in-line skating, skateboarding and roller skating to protect against bodily injury during falls on pavement or other hard surfaces. The conventional knee and elbow pad designs comprise a padded layer which is strapped about the user's knee or elbow together with a concaval wear cap which is secured to the front of the padded layer. The wear cap is typically formed of a hard plastic material, such as high molecular weight polyethylene, having a smooth surface which permits the wear cap to slide over the pavement. This dissipates some of the energy from a fall.
The older designs for knee/elbow pads employed rivets or grommets to secure the wear caps to the front of the padded layers. One limitation of those designs is that the users could not remove the wear caps; thus when the caps wore out it was necessary to throw away and replace the knee or elbow pads, which were expensive. More recently, manufacturers have provided removable wear caps so that when the caps wear down they can be replaced with new ones without having to throw away the expensive pads. One such prior design employs complementary hook and loop fasteners (Velcro.RTM., for example) for releasably attaching the wear caps to the pads.
The Velcro.RTM. fastening system was invented by a Swiss engineer, George de Mestral, who conceived of the idea after pulling cockleburs from his trousers and his dog's hair one day in the early 1940's. Examination of the burs under a microscope revealed arrays of tiny hooks that would attach to anything looplike. The trademark name Velcro is an acronym for the French words "velours" and "crochet," which mean "velvet" and "hook," respectively. The present-day Velcro.RTM. fastening system provides pads carrying miniature rows of hooks and loops which are from 15 thousandths to 100 thousands of an inch high. A two-inch square piece may contain as many as many as 3,000 hooks and loops, although only about one-third may be engaged when the pads are together. Such a two-inch square piece may resist a force of up to 45 pounds per square inch of shear force applied parallel to the base of the hooks. The hooks and loops can be detached with less force when pulled at an oblique angle because the diagonal tugging disconnects only a single row apart a time rather than the entire complement of hooks and loops.
Conventional hook and loop fasteners in which the pointed hook ends are randomly oriented resist shear forces equally in all directions parallel to the base. When a tension force is applied at a right angle to the base, the fasteners have an unfastening resistance of up to 20 pounds per square inch.
There are a number of limitations and disadvantages in the use of conventional hook and loop fasteners for attaching wear caps in protection devices such as knee/elbow pads. One is that adhesives do not work well for attaching the hook and loop fabric sides to either the padding or the wear cap. Another problem is that conventional hook and loop fasteners are not strong enough to securely hold the wear caps in place such that they can be dislodged from aggressive forces encountered during falls onto hard pavement. A further problem is that the aggressive heavy duty hooks tend to wear out over a short period of time such that if the user attempts to replace the wear cap with one having a new strip of loop fabric it would not work properly because the worn hooks will not securely engage the fabric. In addition, the heavy duty hooks tend to shred and eventually wear out the loop fabric because of the aggressive pulling forces that are generated after removing the caps only a few times for adjustment or replacement. This leads to further deterioration of the fastening system, thus making it necessary to replace the entire expensive pad, if the loop fabric were to be attached to the pad.
A further problem with conventional protective devices which use hook and loop strips to attach the wear caps is that the strips tend to lock up before the user can get the cap all the way on to the padded layer. To avoid this problem manufacturers have made the caps flatter and with less curvature, but this is undesirable in that the wear pads then do not properly conform about the user's knee or elbow.
The need has therefore been recognized for a protective device which obviates the foregoing and other limitations and disadvantages of the prior art knee/elbow pads. Despite the various knee/elbow pads in the prior art, there has heretofore not been provided a suitable and attractive solution to these problems.